Seismic Design of Multi-Storey Buildings by Using Stability Coefficient Response Spectra via the FSSDOF System

Earthquake resistant structures must meet the conditions specified in the standard seismic codes of the country. Force-based method is a commonly used method for design and analysis of buildings. The method requires preliminary design of elements to determine the period of the building. Furthermore, iteration can be carried out to satisfy inter-storey drift limits specified by the seismic codes. Recently developed “first storey single degree of freedom”(FSSDOF) approach by Mousavi and Şensoy, is used to determine base shear according to Stability Coefficient (SC) using “Stability Coefficient Response Spectrum” (SCRS). SCRS is formed due to period dependence feature of stability coeffient and spectral acceleration is plotted versus SC for an inverted pendulum with a known height. FSSDOF is used as a single degree of freedom (SDOF) system since the height of first storey rarely changes during the design process and the shear force acting on the first storey is directly equal to the base shear. In order to create response spectra, dynamic response of SDOF systems is analysed by using Newmark’s Method for linear systems. In this thesis, two structures of different heights, five storey and nine storey, were designed and analyzed for different yield strength reduction factors by force based design. Then by calculating the equivalent SC of the fundamental vibration period, base shears were obtained by conventional response spectra and SC response spectra were compared. Higher base shear values were obtained by SCRS since P-delta effect is inherited within the equation of motion. Keywords: stability coefficient response spectrum, first storey single degree of freedom system, force based design, multi-storey buildings.